Re: Probability Doubt

Posted by MI on May 28, 2013; 6:44am
URL: http://discussion-forum.276.s1.nabble.com/Probability-Doubt-tp7581368p7581369.html

Number of straight lines = N ( when all points are non-collinear) - N ( multiple counts due to 5 collinear points) + 1  

= 12C2 -5C2 +1

1 for the line containing those 5 collinear points


For triangles = 12C3 - 5C3

5C3  is the number of triangles which were not made due to collinear points